The new coronavirus is a spiky little ball about 100 nanometers in diameter (less than a thousandth the thickness of a hair) that is essentially made up of proteins, genetic material and, in the case of Sars-CoV-2, lipids. To make a vaccine, you need to borrow at least one of these parts from the pathogen.
The easiest way to do this is to use the whole package, that is, make lots of virus particles, kill these viruses and inject them into the person to be immunized. These are inactivated vaccines like Coronavac, which were developed in collaboration with the Chinese pharmaceutical company Sinovac and the Butantane Institute in São Paulo. A similar method is used to get the flu shot.
In this process, the virus produced in the laboratory is chemically treated with a formaldehyde solution (formaldehyde), which kills it without destroying its structure. This allows it to be recognized in the body by the immune system, which triggers the formation of the immune memory. This allows the organism to react more efficiently to a real infection.
While viruses for the flu vaccine are created by infecting chicken eggs, those from Coronavac multiply in Vero-type cells. These cells were collected from the kidney of an African monkey of the genus Chlorocebus in the 1960s and have been grown in the laboratory ever since.
In addition to the inactivated virus, the vaccine syringe also contains water, some salts, stabilizers and the adjuvant aluminum hydroxide, which strengthens the body’s immune response.
The proposal by the pharmaceutical companies Pfizer in collaboration with BioNTech and Moderna goes in a different direction. Here the big star is the virus’ genetic material, which is made up of RNA.
One of the explanations for the speed at which these vaccines are made and tested is that they are made using chemical synthesis without depending on living organisms, as is the case with inactivated vaccines.
The technology that was not used in vaccines for humans until then is to use a segment of the virus’s genetic material, in this case the one responsible for synthesizing a protein, the S of the spike, the structure that is respiratory cells and subsequent invasion are responsible for binding the virus to the virus.
Fortunately, in this case, too, the vaccine is unable to develop the disease, as there is no information on how to make a whole virus.
This RNA is enclosed in a small bubble of lipids, nanoparticles that have been specially designed and brought together to have two properties: to maintain the integrity of the RNA and, after injection, to “deliver” the RNA directly into the person’s cells enable.
Injection of RNA vaccines contains other important molecules such as polyethylene glycol that allow the nanoencapsulated RNA to last longer in the human body and maintain the potential of the vaccine. The sucrose also present helps with stability and integrity at different temperatures.
The contents of the Pfizer vaccine bottle must be diluted with 0.9% saline, which is also used, for example, to infuse medication, clean wounds, rinse the nose and wash contact lenses.
In the rough negotiations between Pfizer and the federal government, it was pointed out, among other things, that the pharmaceutical company did not supply the diluent and cannot be held responsible for any side effects.
There have been cases of anaphylactic reactions (including difficulty breathing, swelling, and other symptoms) among cases vaccinated with the Pfizer immunizer, but saline solution is unlikely to be the culprit.
In the cytoplasm, inside the cell, the RNA is read and, based on its instructions, viral proteins are made that alert the immune system and prepare it for any infection.
There is no risk of altering the human genome for two reasons: First, the RNA does not even reach the nucleus of the cell, in which the chromosomes are stored that contain our genetic information. The second is that our genetic information is encoded as DNA, not RNA.
Vaccines from the Oxford-AstraZeneca consortium and the Gamaleya Institute in Russia use DNA. However, it is an encapsulated version of the Sars-CoV-2 genetic material within another type of virus, the adenovirus.
In these cases, the goal is also to produce the infamous S protein and activate the immune system. The virus in question is called “recombinant” because it combines genetic information from different sources – the adenovirus itself and that introduced by scientists.
The big advantage over RNA vaccines is the price and storage in conventional refrigerators instead of freezers at -20 ° C (Moderna vaccine) or -70 ° C (Pfizer).
Ingredients in this type of vaccine include stabilizers containing polysorbate 80 (also used in ice cream), as well as molecules that are widely used in drugs and other vaccines that help keep the virus particles intact regardless of the pH of the solution or the concentration is retained by ions in the solution.
Understand the components that can appear in antiviral vaccines
Virus inactivated
Virus particles that have been killed after chemical treatment and cannot cause disease, but trigger an immune response
RNA lipid nanoparticles
Segment of the genetic material of the virus encapsulated in lipid vesicles; Viral proteins are produced in the body that activate the immune system
Recombinant adenovirus
Low infectious virus particles that contain a version of the genetic material of the new coronavirus that can produce viral proteins
Saline solution
It consists of water and 0.9% sodium chloride (table salt) and is used to dilute some vaccines. In other cases, this dilution can also be carried out with purified water.
Adjuvants
Compounds such as aluminum hydroxide, which can increase the activation of the immune system towards the vaccine and increase the protective potential of the vaccine
Preservatives
Molecules, like sucrose, that protect the components of the vaccine when frozen
Chelators
They act like a kind of molecular sponge and trap ions like magnesium and calcium
plug
Molecules like TRIS that help maintain the pH of the solution and keep it from becoming too acidic or alkaline
Stabilizers
Molecules that ensure the structure of the particles that make up the vaccine, like polysorbate 80, are also used in ice cream to help slow the melting process
Source: FDA, NIH, CDC, Medum